1. Field of the Invention
The present invention concerns a pre-diffused or pre-implanted logic circuit wherein the speed of change between two logic states, 0 and 1, can be adjusted or set by a choice of components, made during the metallization that customizes this pre-diffused or pre-implanted circuit.
2. Description of the Prior Art
Customizable circuits are circuits that include a plurality of discrete components (diodes, transistors etc.) or elementary functions (logic operators, inverters etc.) that are not interconnected: the network of metallic interconnections is deposited when the user has provided his electrical diagram, which personifies this general-purpose circuit. Most usually, only a fraction of the circuits available is used to form the circuit used.
Customizable circuits of this type are called CICs (custom integrated circuits) or, generically, "pre-diffused" circuits, although it is more precise to speak of "pre-implanted" circuits when the circuit is made on GaAs or on materials of the III-V group. The invention concerns pre-diffused circuits on Si or pre-implanted circuits on GaAs.
The pre-implanted components and functions have characteristics, such as their speed, or cut-off frequency, that are set by the technology used: the interconnections that are deposited subsequently cannot change these characteristics, they can only group together existing components or leave aside unused components. Consequently, the circuits made have performance characteristics equal to that of the discrete components and the elementary functions that form them, and these performance characteristics are fixed by the technology used.